Context: Limited evidence is available on the real-world effect of insulin degludec (IDeg) in type 1 diabetes (T1D), using continuous glucose monitoring (CGM)-derived metrics. Objective: To assess the real-world effect of switching to IDeg from other long-acting insulins on time in ranges (TIRs) measured by CGM, metabolic control, and insulin dose for people with T1D. Design: This retrospective multicenter study encompassed five time points during a 12-month pre-switch of IDeg and a 12-month follow-up period. For each visit, clinical and CGM data were collected to evaluate temporal trends in glycemic outcomes. Participants: Of 753 persons with T1D who were assessed for eligibility, 486 persons were included, mostly men (61.5%), 47.4 (16.9) years old and diabetes duration of 23.8 (14.2) years at IDeg-initiation. Main Outcome Measure: Primary outcome was the evolution of percent TIR (70-180 mg/dL or 3.9-10.0 mmol/L, TIR) before versus after switch to IDeg. Results: TIR over 24 h increased at 12 months versus baseline (56.7% vs. 52.3%, P < 0.001), mostly during daytime. Time <54 mg/dL (<3.0 mmol/L) over 24 h decreased at 12 months versus baseline (2.02% vs. 2.86%, P < 0.001), mostly during nighttime. Glycated hemoglobin (7.9% vs. 8.1%, P < 0.001) and coefficient of variation (40.0% vs. 41.5%, P < 0.001) improved at 12 months versus baseline. Mean daily basal, bolus and total insulin doses decreased at 12 months (P < 0.001 for all vs. baseline). Conclusions: This retrospective real-world study reports that switching basal insulin significantly improved time spent in glucometric ranges and glycemic variability in the studied population of people with T1D. Clinical Trial Registration number: NCT05434559.
Keywords: Continuous glucose monitoring; Glycemic control; Insulin degludec; Real-world data; Type 1 diabetes mellitus.